U.S. Pat. No. 4,339,522 describes the use of certain Meldrum's diazo compounds as sensitizers for deep ultraviolet when incorporated in resins.
Application Ser. No. 508,642, U.S. Pat. No. 4,522,911 assigned to the same assignee as the present application, discloses the use of diazohomotetramic acid compounds as deep ultraviolet sensitizers.
A resist system for use in lithography using deep ultraviolet light must simultaneously possess several characteristics. One, the system must have a sensitivity which allows it to be used at acceptable exposure and development times. Two, the system should have no spectral sensitivity in the longer wavelength regions, that is, above 300 nm. When there is no spectral sensitivity in that range, the need for inefficient spectral filtration of the radiation source is eliminated. Three, the formulated system should have an optical absorption consistent with the ability to generate photoresist images. Four, the system should have chemical and physical characteristics compatible with micro fabrication processes, such as resistance to reactive ion etching. Finally, the sensitizer should have photoproducts that are transparent at the irradiation frequency.
Because of the numerous demands which such a system must simultaneously meet, the prior art systems all leave something to be desired and fail to meet these stringent requirements completely.